Methods and apparatus for weighing portions are known. Weighing systems based on batching on peaces/units are known and can with a considerable accuracy be weighed so that portions will neither be too large nor to too small within a predetermined limit.
In GB A 1 575 683 a batch weighing apparatus is described for automatic weighing successive batches of material and products from bulk in an automatic operating cycle, said apparatus including a rough feed means operable to feed a major part of each batch into a weigh-pan of the apparatus in a fast rate and fine feed means operable to feed remaining part of the batch.
DE A1 1575683 describes an apparatus for making portions of tobacco in a similar way, i.e. in a first step a rough weight limit is obtained and subsequently the portion is completed with a fine weighing.
Several other weighing methods and devices have been described such as in U.S. Pat. No. 4,901,807, where a device for providing a quantity of product with predetermined weight to a collecting means is disclosed. The U.S. Pat. No. 4,010,809 discloses a method for weighing product pieces of irregular size and weight into batches, where smaller pieces are guided into a separate lane for reaching a predetermined weight. An apparatus for weighing and delivering products like potatoes is disclosed in the U.S. Pat. No. 3,720,276, where the products are conveyed separately in two weight ranges to a receptacle in order to obtain a number of products for packing within a predetermined weight range. A UK patent document discloses an apparatus for quantifying tobacco into doses using a coarse-dosing device and a fine dosing device to obtain a desired weight of tobacco in a dose in a weighing compartment. Finally, the U.S. Pat. No. 4,313,507 claims a method for grouping a population of articles into a portion having a weight at least equal to a desired target weight.
The problem with these methods and devices is that it they are not suited for making more than one portions simultaneously. Further, a portion with too large overweight cannot be rejected without performing a new rough and fine feeding.
There is therefore a need for an apparatus for weighing a plurality of portions simultaneously, whereby portions with to large overweight may be rejected and returned back to the main stream without rejecting the whole portion.